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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 25 (1998), S. 1630-1636 
    ISSN: 1619-7089
    Keywords: Key words: Technetium-99m diaminocyclohexane ; Cyclosporine nephrotoxicity ; Chromium-51 ethylene diamine tetra-acetic acid ; Glomerular filtration rate ; Plasma clearance rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Technetium-99m diaminocyclohexane (DACH) is a new tubular agent excreted via a cationic transport mechanism, like cyclosporine-A (CsA). It is expected that 99mTc-DACH will permit effective assessment of tubular function in CsA-treated patients. To establish the pharmacokinetic characteristics of 99mTc-DACH and to ascertain whether this new agent is useful in CsA-treated patients, 11 healthy volunteers and 15 CsA-treated patients underwent renal imaging and clearance studies using 99mTc-DACH and chromium-51 ethylene diamine tetra-acetic acid (EDTA). 99mTc-DACH yielded satisfactory dynamic renal images in all participants. The mean plasma clearance of 99mTc-DACH was significantly greater than that of 51Cr-EDTA in volunteers (109.4±19.7 ml/min versus 86.6±13.7 ml/min, P〈0.05). However, the urinary excretion of 99mTc-DACH at 90 min was significantly lower than that of 51Cr-EDTA (46.1%±9.3% versus 53.1%±8.6%, P〈0.05), most probably due to its partial parenchymal retention. The elimination half-life of 99mTc-DACH was significantly increased in CsA-treated patients in comparison to volunteers, and consequently the plasma clearance values were significantly suppressed in these patients, in contrast to 51Cr-EDTA and endogenous creatinine clearance values. In conclusion, our findings indicate that 99mTc-DACH, as a sensitive marker of cationic tubular function, could be used to monitor renal haemodynamics in patients receiving CsA treatment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 23 (1996), S. 568-570 
    ISSN: 1619-7089
    Keywords: Technetium-99m sestamibi ; Multidrug resistance ; P-glycoprotein ; Glutathione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An in vitro study was designed to evaluate the uptake of sestamibi (MIBI) in P-glycoprotein (Pgp) and glutathione-associated (GSH) multidrug-resistant (MDR) cell lines. MIBI uptake was studied in various human breast carcinoma cell lines, i.e. in wild-type (MCF7/wt) cells, in adriamycin-resistant (MCF7/adr) cells which express Pgp and in melphalan-resistant (MCF7/mph) cells with increased levels of GSH. The effects of buthiomine sulphoximine (BSO) and verapamil on MIBI uptake were also studied in the MCF7/mph and MCF7/adr cells respectively. The cells were incubated for 1 h with a dose of 0.1 MBq thallium-201 and technetium-99m MIBI. Both MIBI and201Tl uptakes were higher for MCF7/mph cells than for the other cells studied. The mean MIBI uptake in MCF7/adr cells was significantly lower than that in MCF7/wt cells (1.9%±0.5% vs 3.1%.0.6%;P 〈0.01). Verapamil treatment increased the MIBI uptake in MCF7/adr cells (to 2.6%.0.3%;P 〈0.05). Treatment of MCF7/mph cells with BSO resulted in a significant reduction in GSH content (from 243.2±81.1 nmoUmg protein to 17.6±4.4 nmol/mg protein;P 〈0.001). However, MIBI uptake in BSO-treated and untreated MCF7/mph cells was similar (4.43%±0.5% and 5.93%±1.7%, respectively;P 〉0.1). This study suggests that the uptake of MIBI is not diminished by glutathione-associated drug resistance and that MIBI uptake in a tumour sample does not necessarily indicate that a cancer is sensitive to drugs.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 23 (1996), S. 1556-1556 
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 26 (1999), S. 900-902 
    ISSN: 1619-7089
    Keywords: Key words: Radionuclide renography ; Renal function ; Technetium-99m ethylenedicysteine ; Effective renal plasma flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. It has been shown that technetium-99m ethylenedicysteine (99mTc-EC) clearance displays a strong correlation with orthoiodohippurate clearance and that it is possible to estimate effective renal plasma flow from 99mTc-EC clearance. However, in routine practice, when monitoring renal function of patients by clearance determinations it is imperative to test the reproducibility of the clearance technique in order to decide whether the changes in renal function are related to disease or not. The aim of this study was to test the reproducibility of 99mTc-EC clearance. The study group comprised 13 patients aged between 24 and 58 years (eight female and five male). Two patients had single kidneys due to agenesis and hypoplasia. Plasma creatinine and BUN levels were within the normal range and remained stable between two clearance studies. None of the patients were receiving medication. Two separate multiple sample clearance studies were performed in each patient within a week. The difference between two studies was expressed as a percentage of the mean value of the two studies, and the standard deviation of these percentages represented the precision. The plasma clearance of 99mTc-EC in the first-step studies ranged from 190 ml/min to 561 ml/min with a mean of 411±101 ml/min. The clearances obtained from the second-step studies ranged from 248 ml/min to 552 ml/min, with a mean of 387±94 ml/min. There was no statistically significant difference between the two clearance studies (P〉0.05). There was a mean difference of 5.3% between the first and second clearance studies, and the precision was found to be 12.7%. In conclusion, this study suggested that consecutive 99mTc-EC clearance measurements should be interpreted cautiously.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 27 (2000), S. 713-720 
    ISSN: 1619-7089
    Keywords: Key words: Technetium-99m methoxyisobutylisonitrile ; Thallium-201 ; Thyroid nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. A comparative prospective study of technetium-99m methoxyisobutylisonitrile (MIBI) and thallium-201 with early (15 min) and delayed (90 min for MIBI, 3 h for 201Tl) imaging in the differentiation of thyroid lesions is presented. Forty patients with cold thyroid nodules visualised on 99mTc-pertechnetate scan and with dyskaryotic or atypical epithelial cells verified by fine-needle aspiration biopsy underwent MIBI and 201Tl scintigraphy at 3-day intervals. Subsequent thyroidectomies were carried out in all patients. Semiquantitative analysis was performed using a lesion to non-lesion ratio on early (ER) and delayed images (DR). Additionally, a retention index (RI) was calculated using the formula RI=(DR– ER) × 100/ER. The reproducibility of the method for the early and delayed measurements was tested by analysing intra- and inter-observer variability and repeatability coefficients. Histopathologically, the nodules were found to be well-differentiated thyroid cancer in 21 patients and benign in 19 patients. There was no significant difference in the ER between malignant and benign lesions for either 201Tl or MIBI (P〉0.05). However, for both agents significant differences were found between malignant and benign lesions with regard to DR (P〈0.01 for 201Tl and P〈0.001 for MIBI) and RI (P〈0.001 for both agents). Statistical comparison of the two agents showed no significant differences (P〉0.05) except with regard to DR and RI in malignant nodules (P〈0.05). A receiver operating characteristic analysis was performed to determine threshold levels for the differentiation of malignant from benign nodules. Following this analysis, ER, DR and RI levels of 1.03, 1.54 and 2 for MIBI and ≤1.42, 1.24 and 5 for 201Tl were selected. Using these threshold levels, the sensitivity, specificity and accuracy of the study were 90.5%, 36.8% and 65% for ER MIBI, 61.9%, 94.7% and 77.5% for DR MIBI, 95.2%, 89.4% and 92.5% for RI MIBI, 85.7%, 47.3% and 67.5% for ER 201Tl, 80.9%, 73.6% and 77.5% for DR 201Tl, and 90.5%, 94.7% and 92.5% for RI 201Tl. In conclusion, the DR for MIBI and 201Tl is superior to the ER in detecting malignant nodules, and the RI for both MIBI and 201Tl is more valuable than the DR in differentiating malignant from benign thyroid nodules.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 27 (2000), S. 351-357 
    ISSN: 1619-7089
    Keywords: Key words: Renal tubular agents – Radionuclide renography – Technetium-99m ethylene dicysteine – Technetium-99m mercaptoacetyltriglycine – Effective renal plasma flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Technetium-99m ethylene dicysteine (EC), a metabolite of ethylene cysteine dimer (ECD), is a new technetium-labelled renal tubular function tracer introduced as an alternative to ortho-iodohippurate (OIH) and with imaging qualities similar to 99mTc-mercaptoacetyltriglycine (MAG3). The elimination of 99mTc-EC is principally via active tubular transport. It is available in lyophilised kit form which can be easily prepared at room temperature, and the compound remains stable for at least 8 h. Both in normal individuals and in patients, plasma clearance of 99mTc-EC has been reported to be around 0.75 of OIH clearance. Thus there is a very strict correlation between 99mTc-EC and OIH clearance, and several algorithms are available to estimate OIH clearance from 99mTc-EC clearance. The renal extraction ratio of 99mTc-EC is 0.70. The distribution volume of 99mTc-EC is twice that of 99mTc-MAG3 (20% of body weight) and slightly higher than that of OIH. The plasma protein-bound fraction of 99mTc-EC (30%) is significantly lower than that of 99mTc-MAG3 and OIH. The same applies to red blood cell binding of 99mTc-EC (5.7%). There is negligible uptake in the liver and intestines. Within 1 h 70% of 99mTc-EC is excreted in the urine. 99mTc-EC provides the same scintigraphic information as 99mTc-MAG3. The lower liver activity makes 99mTc-EC particularly attractive in patients with renal failure. The 99mTc-EC clearance can be accurately estimated from a single plasma sample obtained at 54 min after injection. In conclusion, 99mTc-EC is a suitable renal imaging agent and for some applications is even more attractive than OIH: it provides an index of tubular function and yields high-quality images. The labelling procedure is easy, radiochemical purity is high and the complex is stable for a long time. The extent to which 99mTc-EC is adopted for clinical use will ultimately depend upon its cost and availability.
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